Work function of a metal is \(5.2 \times 10^{-18}~\mathrm{J} \) then its threshold wavelength will be:
1. \(736.7~\mathrm{\mathring A}\)
2. \(760.7~\mathrm{\mathring A}\)
3. \(301~\mathrm{\mathring A}\)
4. \(378.4~\mathring A\)
Remaining quantity (in %) of radioactive element after 5 half-lives is:
1. 4.125%
2. 3.125%
3. 31.1%
4. 42.125%
An engine pumps up 100 kg of water through a height of 10 m in 5 s. Given that, the efficiency of an engine is 60%. If g = 10 ms-2, the power of this engine is:
1. 3.3 kW
2. 0.33 kW
3. 0.033 kW
4. 33 kW
The angular amplitude of a simple pendulum is \(\theta^\circ.\) The maximum tension in its string will be:
1. \(mg(1-\theta_0)\)
2. \(mg(1+\theta_0)\)
3. \(mg(1-\theta_0^2)\)
4. \(mg(1+\theta_0^2)\)
If the electric flux entering and leaving an enclosed surface respectively are \(\phi_1\) and \(\phi_2,\) the electric charge inside the surface will be:
1. \(\frac{\phi_2-\phi_1}{\varepsilon_0}\)
2. \(\frac{\phi_2+\phi_1}{\varepsilon_0}\)
3. \(\phi_2-\phi_1~\varepsilon_0\)
4. \(\varepsilon_0\phi_1+\phi_2\)
During an adiabatic process, the pressure of a gas is found to be proportional to the cube of absolute temperature. The ratio \(\frac{C_P}{C_V}\) for the gas is:
1. \(\frac43\)
2. \(2\)
3. \(\frac53\)
4. \(\frac32\)
Three point charges +q, -2q and +q are placed at points (x=O, y= a, z =O), (x=O, y=O, z=O) and (x = a, y = 0, z = 0), respectively. The magnitude and direction of the electric dipole moment vector of this charging assembly are:
1. | \(\sqrt{2qa}\) Along+y children |
2. | \(\sqrt{2qa}\) Along the line joining points (x=0, y=0, z=0) and (x=a, y=a, z=0) |
3. | qa along the line joining points (x=0, y=0, z=0) and (x=a, y=a, z=0) |
4. | \(\sqrt{2qa}\) Along + x direction |
A block \(B\) is pushed momentarily along a horizontal surface with an initial velocity \(v.\) If \(\mu\) is the coefficient of sliding friction between \(B\) and the surface, block \(B\) will come to rest after a time.
1. \(\frac{v}{g\mu}\)
2. \(\frac{g\mu}{v}\)
3. \(\frac{g}{v}\)
4. \(\frac{v}{g}\)
To get three images of a single object, we should have two plane mirrors at an angle of:
1. \(60^\circ\)
2. \(90^\circ\)
3. \(120^\circ\)
4. \(30^\circ\)
A particle of mass \(M\) and charge \(Q\) moving with velocity \(v\) describes a circular path of radius \(R\) when subjected to a uniform transverse magnetic field of induction \(B.\) The work done by the field, when the particle completes one full circle, is:
1. \(\frac{Mv^2}{R}2\pi R\)
2. zero
3. \(BQ2^{\pi R}\)
4. \(BQv2^{\pi R}\)